The present disclosure relates generally to seal assemblies, and more particularly to seal rings for use in gas turbine engines.
Honeycomb and knife-edge seals can be used to form a seal at the interface between rotating and static components within the turbine section of a gas turbine engine. Over time, knife-edge seals can wear a trench into the honeycomb causing gaps and sporadic increased leaks over time.
Floating non-contact seal (a.k.a., hydrostatic seal) configurations allow radial motion of shoe components relative to a rotating component. Seal rings can vary a gap between the sealing element and a rotating component by adjusting in response to the change in pressure across the sealing element. A shoe component of the floating non-contact seal is drawn radially inward and outward (toward and away) from the rotating component in response to the pressure across the sealing element. The shoe is supported on one end by spring-like beams. The shoe has a distributed load that is acted over the shoe from flow of a fluid passing across the seal. Because of this, the shoe effectively deforms as a cantilevered beam creating clearance variation with the rotating component thereby reducing sealing effectiveness. The shoe is configured such that the free end of the shoe deflects further inboard and outboard than the fixed end of the shoe. Due to this, the sealing effectiveness of the shoe is limited and a propensity for clash with the rotating component is increased.
Structures and configurations of seal rings are the subject of the following commonly owned U.S. Patent Publications US2016/0130963A1, US2015/0322816A1, and US2015/0285152A1 (incorporated by reference herein in their entireties).